Subject: Re: adjusted points...idles fast now

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In a message dated 08/26/2002 5:59:35 PM Pacific Daylight Time,
3haw-@bluefrognet.net writes:

Can you continue on account of I have an old strobe light I would like to
use on my Ambo.

I erred ever so slightly on my earlier post. The left side cylinder (your
left while you sit in the saddle) is the "number two" cylinder. Not number
one. However, yes, it is still the same cylinder you use to match up the
timing marks on the front pulley.

You want to use a stroboscopic timing light. Good. Follow my earlier
instructions to set the static timing or, just go for it if the bike is
running now.

Your strobe has to have some sort of pickup for the left side spark wire or
"secondary" wire. (Primary ignition is the 12v skinny stuff from your key to
the coil to the distributor points. Secondary ignition is the big, fat, tens
of thousands of volts in the wires from the coil to the distributor to the
spark plug.) Either you have an "inductive' pickup which wraps around the
left cylinder secondary lead, or you have an older "hard wire" setup which
requires you to remove the spark plug lead and put the pickup in series.

Run the engine and point the strobe at the timing marks. Caution: EVERYONE
who has every timed a hot running Guzzi motor has burned the inside of their
forearm on the hot exhaust header. Don't say I didn't warn you! We can all
compare burn scars at the next rally.

There should be four marks on the pulley. (page 22 if you have the old
Premier Motors shop manual.) They appear as two pairs of close marks. As
you face backwards from the front looking at the engine, the pulley turns
clockwise. The first mark to reach the casting arrow is FULL ADVANCE, 33
degrees before TDC by my book. There are variations and the older Ambassador
may be a little less than the Eldorado. Check out several book resources.
The second mark is probably 25 degrees before TDC, the third mark is probably
5 degrees before TDC and the last mark will be TDC. (Top Dead Center or PMS
punte morte superiore in Italian when the left piston reaches the top center
of its stroke on the compression stroke of the cycle.)

You may certainly find small variations of this plan in various books and
among various mechanics. Remember also that these specs were all planned
back in the 60s and 70s when we had real gasoline. This modern crap
generally requires a few degrees more retarding than the original factory
spec. Also, sagged out distributor springs will allow the system to advance
a little too quickly and cause pinging. So, if your springs are older you
might wish to err on the slightly retarded side. Since the Guzzi motor
spends most of its time in the 3K to 4K operating range, many mechanics
prefer to set the timing at the 33 (or slightly less) full advance mark with
the engine spinning at 4K and then not worry about a few degrees of error
down at the idle end.

BTW, I found a wonderful, relatively cheap timing strobe at JC Whitney. I
has two on-board D cells for power so there is not battery hookup. Only one
secondary inductive wire, so less likely to foul or to trip or to drop on a
hot exhaust. Wonderful in that I can even use it to inspect the timing on my
'46 Guzzi with magneto ignition.

Patrick Hayes
Fremont CA

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<HTML>In a message dated 08/26/2002 5:59:35 PM Pacific Daylight Time, 3haw-@bluefrognet.net writes: 
 
 
<BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Can you continue on account of I have an old strobe light I would like to use on my Ambo. </BLOCKQUOTE> 
 
I erred ever so slightly on my earlier post. The left side cylinder (your left while you sit in the saddle) is the "number two" cylinder. Not number one. However, yes, it is still the same cylinder you use to match up the timing marks on the front pulley. 
 
You want to use a stroboscopic timing light. Good. Follow my earlier instructions to set the static timing or, just go for it if the bike is running now. 
 
Your strobe has to have some sort of pickup for the left side spark wire or "secondary" wire. (Primary ignition is the 12v skinny stuff from your key to the coil to the distributor points. Secondary ignition is the big, fat, tens of thousands of volts in the wires from the coil to the distributor to the spark plug.) Either you have an "inductive' pickup which wraps around the left cylinder secondary lead, or you have an older "hard wire" setup which requires you to remove the spark plug lead and put the pickup in series. 
 
Run the engine and point the strobe at the timing marks. Caution: EVERYONE who has every timed a hot running Guzzi motor has burned the inside of their forearm on the hot exhaust header. Don't say I didn't warn you! We can all compare burn scars at the next rally. 
 
There should be four marks on the pulley. (page 22 if you have the old Premier Motors shop manual.) They appear as two pairs of close marks. As you face backwards from the front looking at the engine, the pulley turns clockwise. The first mark to reach the casting arrow is FULL ADVANCE, 33 degrees before TDC by my book. There are variations and the older Ambassador may be a little less than the Eldorado. Check out several book resources. The second mark is probably 25 degrees before TDC, the third mark is probably 5 degrees before TDC and the last mark will be TDC. (Top Dead Center or PMS punte morte superiore in Italian when the left piston reaches the top center of its stroke on the compression stroke of the cycle.) 
 
You may certainly find small variations of this plan in various books and among various mechanics. Remember also that these specs were all planned back in the 60s and 70s when we had real gasoline. This modern crap generally requires a few degrees more retarding than the original factory spec. Also, sagged out distributor springs will allow the system to advance a little too quickly and cause pinging. So, if your springs are older you might wish to err on the slightly retarded side. Since the Guzzi motor spends most of its time in the 3K to 4K operating range, many mechanics prefer to set the timing at the 33 (or slightly less) full advance mark with the engine spinning at 4K and then not worry about a few degrees of error down at the idle end. 
 
BTW, I found a wonderful, relatively cheap timing strobe at JC Whitney. I has two on-board D cells for power so there is not battery hookup. Only one secondary inductive wire, so less likely to foul or to trip or to drop on a hot exhaust. Wonderful in that I can even use it to inspect the timing on my '46 Guzzi with magneto ignition. 
 
Patrick Hayes 
Fremont CA

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Subject: Re: adjusted points...idles fast now

Author: Patrick Hayes

Date: Aug 26, 2002, 9:50 PM

Post ID: 1710886625

Entire thread: